The present specification provides novel compositions of matter and novel methods of their preparation.
The present specification particularly relates to novel analogs of a known pharmacological agent, khellin, also known as "visamin", and structurally related antiatherogenic furochromones and other benzopyrans. Chemically, khellin is a furochromone. Furochromones are characterized generally by the structural formula IV. Specifically, khellin is the furochromone of formula V, and is trivially named 7-methyl-4,9-dimethoxyfurochromone. Khellin and related furochromones are naturally-occurring substances and have been used in crude form as pharmacological agents for centuries. Khellin is an extract from the plant Ammi visnaga. This plant grows wild in Eastern Mediterranean countries. Aside from khellin, Ammi visnaga is also a source of at least three other known and characterized furochromones, specifically visnagin, khellinin, and ammiol.
As indicated above, khellin exhibits a wide variety of pharmacological actions, rendering this compound a useful agent for numerous pharmacological purposes. For a comprehensive, but somewhat dated, review of the chemistry and physiological action of khellin-related products, see the reports of Huttrer, C. P., et al., Chem. Revs. 48:543-79 (1951) and Aubertin, E., J. Med. Bordeaux 127:821-823 (1950).
One principal action of khellin is its ability to induce relaxation of smooth muscle tissues. Particularly, khellin is known as a potent dilator of coronary blood vessels. This potent coronary vasodilator activity of khellin renders the compound useful in the treatment of angina pectoris and other diseases characterized by coronary artery insufficiency. For a description of the use of khellin in the treatment of such diseases, see Osher, H. L., et al., "Khellin in the Treatment of Angina Pectoris", The New England Journal of Medicine 244:315 (1951). Also the effects of enteric-coated khellin on coronary artery insufficiency is reported by Best, M. M., et al., J. Med. Sci. 222:35-9 (1951). The ability of khellin to relax smooth muscle also extends to gastrointestinal smooth muscle where khellin has been demonstrated to inhibit peristalsis, thus indicating antidiarrhetic potential. See Raymond-Hamet, M., Compt. Rend. 238:1624-6 (1954). Khellin may also be useful for the treatment of gastrointestinal disorders exhibiting a spasmotic component, as suggested by Anrep, G. V., et al., Amer. Heart J. 37:531-542 (1949). Further the antispasmotic effects of khellin on the urethra is reported by Colombo, G., et al., Arch. Sci. Med. 97:71 (1954) and Montorsi, W., et al., Presse Med. 63:81 (1955).
The antispasmotic action of khellin also extends to bronchial smooth muscle, rendering khellin useful in the treatment of asthma and other hypoxic pulmonary diseases. In this regard, see Silber, E. N., et al., "The Effect of Khellin on Cardio-Pulmonary Function in Chronic Pulmonary Disease", published in 1951; Anrep, G. V., et al., "Therapeutic Uses of Khellin", The Lancet, Apr. 26, 1947, pages 557-8.
Khellin has also been reported to exert a hypotensive effect in humans by Jordan, H., Arzneimittel-Forsch 8:141-3 (1958), and 7:82-5 (1957). An additional account of the hypotensive effect of khellin is provided by Lian, C., et al., Acta. Cardiol. (Brussels) 5:373-88 (1950). With respect to overall cardiac effects, however, khellin has been reported to exert a cardiac depressive activity. In this regard see Samaan, K., et al., J. Roy. Egypt Med. Assoc. 33:953 (1950) and J. Pharm. Pharmacol. 1:538-44 (1949).
In addition to its effect on gastrointestinal smooth muscle reported above, khellin is also known as a gastric antisecretory and antiulcer agent. In this regard, the gastric antisecretory activity of khellin is reported by LaBarre, J., Compt. Rend. Soc. Biol. 150:1806-7 (1956) and 150:598-9 (1956).
Numerous other miscellaneous properties of khellin are also reported. For an account of its anthelminic activity see Baytop, O. T., Folia, Pharm. (Turkey) 1:48-9 (1949). For an account of the CNS depressant activity of khellin see Chen, G., Proc. Soc. Expetl. Biol. Med. 78:305-7 (1951). For an account of the cytostatic activity of khellin see Apffel, C. A., Deut. Med. Wochschr. 80:414-16 (1955). Finally, the spermacidal action of khellin is reported by Swayne, V. R., et al., Amer. J. Pharm. 125:295-8 (1953).
Khellin and numerous chemically related furochromones (and derivatives thereof) are also useful in treatment and prevention of atherosclerosis by methods described in U.S. Pat. No. 4,284,569.
Atherosclerosis in mammals is a disease characterized by the deposition of atherosclerotic plaque on arterial walls. While atherosclerosis exhibits many varied forms and consequences, typical consequences of atherosclerotic diseases include angina pectoris, myocardial infarction, stroke and transient cerebral ischemic attacks. Other forms of atherosclerotic diseases include certain peripheral vascular diseases and other ischemias (e.g., bowel and renal).
Medical science now recognizes that certain forms of atherosclerosis may be preventable or reversible. Agents capable of preventing or reversing atherosclerosis are characterized as exhibiting antiatherosclerotic activity. Since serum lipids have a recognized association with atherogenesis, an important class of antiatherosclerotic agents are those with serum lipid-modifying effects. Serum lipids implicated in atherogenesis include serum cholesterol, serum triglycerides, and serum lipoproteins.
With respect to serum lipoproteins, at least three different classes of these substances have been characterized: high density lipoproteins (HDL's), low density lipoproteins (LDL's), and very low density lipoproteins (VLDL's). HDL's are often referred to as alphalipoproteins, while LDL's and VLDL's are referred to as betalipoproteins. The enhancement to HDL levels (hyperalpha-lipoproteinemic activity) is postulated to have direct antiatherosclerotic effects. See Eaton, R. P., J. Chron. Dis. 31:131-135 (1978). In contrast, agents which reduce serum LDL's and serum VLDL's (hypobetalipoproteinemic agents) are also associated with antiatherogenic effects. See Haust, M. D., "Reaction Patterns of Intimal Mesenchyme to Injury and Repair in Atherosclerosis", Adv. Exp. Med. Biol. 43:35-57 (1974), which postulates that serum LDL is a factor in atherosclerotic lesion formation.
Numerous animal models have been developed for assessing antiatherogenic activity. Principal among these are models for assessing hypobetalipoproteinemic activity in the rat, antiatherosclerotic activity in the Japanese quail, and lipoprotein modifying activity in the monkey. For a description of the operation of the hypobetalipoproteinemic rat model, refer to the known methods of Schurr, P. E., et al., "High Volume Screening Procedure for Hypobetalipoproteinemia Activity in Rats", Adv. Exp. Med. Biol. 67: Atherosclerotic Drug Discovery, pp. 215-229, Plenum Press (1975). For a description of the Japanese quail model, see Day, C. E., et al., "Utility of a Selected Line (SEA) of the Japanese Quail (Coturnic Coturnix japonica) for the Discovery of New Anti-Atherosclerosis Drugs", Laboratory Animal Science 27:817-821 (1977).
A suitable primate model for assessing antiatherosclerotic activity of chemical compounds is found in the cynomolgus monkey. In these animals base-line values for VLDL's, LDL's, and HDL's can be determined by controlling diet over a period of several weeks and sampling plasma daily. After establishing control values, the effects of drug treatment are assessed by administering by gavage with a predetermined series of doses of test compounds for a similar period (e.g., two weeks).
The khellin, the khellin-related products of Ammi visnaga, and related furochromones (and derivatives) described in U.S. Pat. No. 4,284,569 are all characterized by pronounced antiatherogenic activity, rendering these compounds useful in the treatment and prophylaxis of atheroscherosis, atherogenic hyperlipoproteinemia (i.e., hypobetalipoproteinemia) and atherogenic hypolipoproteinemia (i.e., hypoalphalipoproteinemia), and the untoward consequences thereof. These compounds exhibit this useful pharmacological activity in both mammalian and non-mammalian species, including humans.
The patients susceptible to the development of atherosclerotic diseases and the untoward consequences thereof are particularly those physically asymptomatic patients manifesting one or more risk factors known to predispose one to disease development. Such risk factors are high serum cholesterol and serum triglycerides, hypertension, obesity, diabetes, and genetic predisposition. Patients manifesting two or more risk factors are deemed to be especially susceptible to atherosclerotic diseases. These khellin-related materials all exhibit pronounced oral pharmacologic activity. Accordingly, in using these compounds for the treatment of atherosclerosis, an oral route of administration, either by conventional oral dosage forms or by mixture with food, represents the preferred method of their systemic administration. Alternatively, however, these compounds may be administered by other convenient routes of administration whereby systemic activity is obtained. These other routes of administration would, accordingly, include rectal, vaginal, subcutaneous, intravenous, and like routes.
In humans, the preferred route of administration is oral, in the form of capsules or tablets containing the drug.
The patient or animal being treated must be given periodic doses of the drug in amounts effective to reduce atherogenic serum lipoproteins (e.g., betalipoproteins) or selectively enhance levels of antiatherogenic serum lipoproteins (e.g., enhancing alphalipoprotein levels, while suppressing, or at least unaffecting, betalipoprotein levels). Such effective dosages are readily determined by methods known in the art. For example, small daily doses of the drug (e.g., 50-100 mg) may be administered initially with higher succeeding doses until levels of atherogenic or antiatherogenic serum lipoproteins are favorably affected. By this regimen, a compound is administered initially at doses as low as about 50 mg per patient per day, with increasing doses up to about 200 mg per patient per day. In the event the antiatherogenic response in a patient being treated at a dose of 200 mg per day is insufficient, higher doses are also utilized to the extent patient tolerance permits further increases in dose.
While the preferred dosage regimen is with single daily dosing of patients, also preferred for obtaining more uniform serum levels of drug are multiple dosages per day (e.g., up to 4-6 times daily). Accordingly, when 4 daily doses of drug are to be administered, each such dose may be about 50 mg per patient per dose (200-300 mg per patient per dose), or higher depending on tolerance.
Similar doses are employed in non-human mammals, e.g., 1-5 mg/kg/day.
4,9-Dimethoxyfurochromones are known in the art. Such known compounds include 7-ethyl, 7-phenyl, 7-propyl, and 7-ethoxycarbonyl analogs described by Schonberg, A., et al., JACS 72:1611-17 (1950); 7-.gamma.-pyridyl analogs, described by Schonberg, A., JACS 77:5439 (1955); 7-furanyl analogs, described by Musante, C., et al., Pharmaco. (Pavie) Ed. Sci. 15:81-94 (1960); 7-carboxyaldehyde analogs, described by Mustafa, A., et al., J. Org. Chem. 26:886 (1961). Also, 6-substituted 4,9-dimethoxyfurochromones are known. See, for example, the compounds described by Abu-Shady, H., UAR J. Pharm. Sci. 11:283 (1970).
4-Methoxy-7-aminomethylenefurochromones are also known in the art. See Abu-Shady, H., et al, J. Pharm. Belg. 33:397 (1978).
A wide variety of antiatherosclerotic furochromones are described in U.S. Pat. No. 4,284,569.